A comprehensive study of Al-Cu-Mg system reinforced with nano-ZrO2 particles synthesized by powder metallurgy technique.

More focus has recently been placed on enhancing the strength, elastic modulus, coefficient of thermal expansion (CTE), wear and corrosion resistance, and other qualities of aluminum (Al) alloys by varying the quantity of ceramics added for a range of industrial uses. In this regard, Al-4.2-Cu-1.6Mg matrix nanocomposites reinforced with nano-ZrO2 particles have been created using the powder metallurgy approach. The microstructure and particle size distributions of the produced powders were analyzed using a diffraction particle size analyzer, XRD, TEM, and SEM. To achieve good sinterability, the powders were compacted and sintered in argon. The sintered nanocomposites' mechanical, elastic, and physicochemical characteristics were measured. Additionally, the behavior of corrosion, wear, and thermal expansion were examined. The results showed a decrease in the particle sizes of the Al-Cu-Mg alloy by adding ZrO2 nanoparticles up to 45.8 nm for the composite containing 16 wt.% ZrO2. By increasing the sintering temperature to 570 °C, the densification of nanocomposites was enhanced. Also, the coefficient of thermal expansion and wear rate remarkably decreased by about 28 and 37.5% by adding 16 wt.% ZrO2. Moreover, microhardness yield, strength, and Young's modulus were enhanced to 161, 145, and 64%, respectively, after adding 16 wt.% ZrO2. In addition, increasing the exposure time was responsible for decreasing the corrosion rate for the same sample.

Blood biomarkers for differential diagnosis and early detection of pancreatic cancer.

Pancreatic cancer is currently the most lethal tumor entity and case numbers are rising. It will soon be the second most frequent cause of cancer-related death in the Western world. Mortality is close to incidence and patient survival after diagnosis stands at about five months. Blood-based diagnostics could be one crucial factor for improving this dismal situation and is at a stage that could make this possible. Here, we are reviewing the current state of affairs with its problems and promises, looking at various molecule types. Reported results are evaluated in the overall context. Also, we are proposing steps toward clinical utility that should advance the development toward clinical application by improving biomarker quality but also by defining distinct clinical objectives and the respective diagnostic accuracies required to achieve them. Many of the discussed points and conclusions are highly relevant to other solid tumors, too.

Noninvasive Discrimination of Low and High-risk Pancreatic Intraductal Papillary Mucinous Neoplasms.

OBJECTIVE: To propose a noninvasive diagnostic approach, which allows reliable distinction between low- and high-risk pancreatic intraductal papillary mucinous neoplasms (IPMNs). BACKGROUND: IPMNs are identifiable precursor lesions of pancreatic cancer, of which surgical resection is warranted prior to the development of invasive carcinoma, but low-grade IPMNs should not be unnecessarily resected. However, diagnostic tools that preoperatively enable accurate risk stratification of IPMNs are missing. METHODS: This single-center, retrospective cohort study included 56 patients who underwent surgical resection for IPMN including 18 low-risk (low-grade) and 38 high-risk (high-grade/invasive carcinoma) IPMNs, from whom clinical features and serum samples were prospectively obtained. An antibody microarray platform was used to analyze the serum proteome. Based on serum markers and selected clinical characteristics support vector machine models were constructed to predict the risk of IPMN malignancy. RESULTS: A serum protein signature discriminating low- and high-risk IPMN patients was identified. Combinations of established clinical features and the newly identified serum biomarkers correctly distinguished low- and high-risk IPMNs in 93% on 1000-fold cross-validation. CONCLUSIONS: This study highlights the synergistic predictive value of combining a novel serum protein signature with conventional clinical characteristics to risk-stratify IPMN patients. If these findings are supported by larger validation studies, they might enable more rational decision-making in clinical management of IPMN patients in conjunction with clinical guidelines.

Expression profiling of primary cultured buffalo granulosa cells from different follicular size in comparison with their in vivo counterpart.

This study aimed to: (i) characterize cultured granulosa cells (GCs) from different follicle sizes morphologically and molecularly; and (ii) select a suitable model according to follicular size that maintained GC function during culture. Buffalo ovaries were collected from a slaughterhouse and follicles were classified morphologically into: first group ≤ 4 mm, second group 5-8 mm, third group 9-15 mm and fourth group 16-20 mm diameter. GC pellets were divided into two portions. The first portion served as the control fresh pellet, and the secondwas used for 1 week for GC culture. Total RNA was isolated, and qRT-PCR was performed to test for follicle-stimulating hormone receptor (FSHR), cytochrome P450 19 (CYP19), luteinizing hormone/choriogonadotropin receptor (LHCGR), proliferating cell nuclear antigen (PCNA), apoptosis-related cysteine peptidase (CASP3), anti-Müllerian hormone (AMH), and phospholipase A2 group III (PLA2G3) mRNAs. Estradiol (E2) and progesterone (P4) levels in the culture supernatant and in follicular fluids were measured using enzyme-linked immunosorbent assay (ELISA). Basic DMEM-F12 medium maintained the morphological appearance of cultured GCs. The relative abundance of FSHR, CYP19, and LHCGR mRNAs was 0.001 ≤ P ≤ 0.01 and decreased at the end of culture compared with the fresh pellet. There was a fine balance between expression patterns of the proliferation marker gene (PCNA) and the proapoptotic marker gene (CASP3). AMH mRNA was significantly increased (P < 0.001) in cultured GCs from small follicles, while cultured GCs from other three categories (5-8 mm, 9-15 mm and 16-20 mm) showed a clear reduction (P < 0.001). Interestingly, the relative abundance of PLA2G3 mRNA was significantly (P < 0.001) increased in all cultured GCs. E2 and P4 concentrations were significantly (P < 0.001) decreased in all cultured groups. Primary cultured GCs from small follicles could be a good model for better understanding follicular development in Egyptian buffaloes.

Relationship Between Heat Shock Protein Expression and Obesity With and Without Metabolic Syndrome.

Background: Obesity is considered a chronic inflammatory disease in which the physiological mechanism responsible for reducing inflammation is weakened, prompting low-grade inflammation throughout the body. One of the key stress response systems that is dysregulated in obesity is the heat shock response, which is a critical defense mechanism that is activated in stressful conditions. Obesity is primary to metabolic syndrome (MetS) as it appears to lead to the increase in other MetS risk factors. Aim of the Study: We aimed to investigate the different expression levels of intracellular heat shock protein (iHSP) 70 and iHSP27 in obese patients with and without MetS and compare these levels to those of a lean control group. Patients and Methods: One hundred ten lean subjects were compared with 44 obese subjects without MetS and 56 obese subjects with MetS. HSP70 and HSP27 mRNA expression levels were measured by quantitative real-time polymerase chain reaction. Results: iHSP70 mRNA expression was significantly higher in obese subjects without MetS than in lean subjects (p = 0.04), whereas iHSP70 mRNA expression was significantly lower in obese subjects with MetS than in those without MetS (p = 0.02) as well as in those in the lean group (p = 0.03). iHSP27 mRNA expression was significantly lower in obese subjects with MetS than in those without MetS and in lean subjects (p = 0.037 and 0.031, respectively). Conclusion: We conclude that the intracellular expression levels of HSP70 and HSP27 may play an important role in the pathogenesis of MetS.

Effect of glycemic gap on short term outcome in critically ill patient: In zagazig university hospitals.

Both admission Blood glucose and previous glycemic state may affect critically ill patients; So Glycemic gap may be a good indicator of ICU outcomes. This study investigated the effect of glycemic gap on short term outcome in critically ill patient and the value of incorporation of the Glycemic Gap into the APACHE-II on its discriminative performance. SUBJECTS AND METHODS: This cross sectional study was conducted in medical ICU of Zagazig University Hospitals, March 2018 to September 2018; total numbers of 240 critically ill patients admitted to ICU were enrolled in. All of them were subjected to: full history taking, clinical examination, routine investigations, random blood sugar, hemoglobin A1c. ADAG, Glycemic Gap and APACHE II were calculated. RESULTS: Elevated glycemic gap was associated with an increased ICU mortality and APACHE-II score was a good predictor of ICU mortality in critically ill patients. CONCLUSIONS: Elevated glycemic gap was significantly associated with an increased ICU mortality that the glycemic gap can be used to assess the severity and prognosis of critically ill patients and their incorporation into the APACHE II score has increased its performance as a predictor of mortality.

Therapeutic efficacy of seaweed extract (Ulva Fasciata Delile) against invasive candidiasis in mice.

Candida is the most frequent common causes of invasive fungal infections and associated with high morbidity and mortality. Most of available antifungal agents have side effects. This opened up new avenues to investigate the antifungal efficacy of active extracts from marine algae. So the aim of this study was to evaluate the protective and the curative effect of Ulva fasciata extract against an invasive candidiasis in mice and to study its underlying mechanism. The active ingredients of Ulva fasciata extract were evaluated using HPLC and GC/MS. Fifty mice were included in current work, and the level of inflammatory markers; Interleukin (IL)-4, IL-12, Interferon-gamma (IFN-γ) and Tumor necrosis factor-alpha (TNF-α) were determined using ELISA kits. Hematological, biochemical and oxidative stress parameters were determined using commercial kits. Moreover, the histopathological examinations were carried on liver, kidney and spleen for all groups. The results obtained showed that treatment with U. fasciata either before or after Candida infection significantly improved the hematological, biochemical alterations and antioxidant status caused by this infection. Furthermore, the U. fasciata reduced histopathological changes induced by Candida as well as it could increase the expression of IL-12 and IFN-γ while minimized the expression of TNF-α and IL-4 in all infected mice compared to infected untreated mice. These data propose that U. fasciata can ameliorate inflammatory reactions related to Candida albicans cytotoxicity via its ability to augment cellular antioxidant defenses by its active compounds.

Secretome profiling of apheresis platelet supernatants during routine storage via antibody-based microarray.

Platelet storage lesions (PSLs) occur during platelet concentrate (PC) storage. Adverse transfusion reactions (ATRs) have been demonstrated to be more frequent in older PCs and removal of the supernatant prior to transfusion reduces their occurrence. Proteomic profiling of PC supernatants was thus performed to identify proteins associated with PSLs and ATRs. Twenty-four PCs were investigated daily from day 0 to day 9 for platelet pre-activation (PPA), platelet-derived extracellular vesicles (PEVs), and platelet function. Using antibody microarrays, 673 extracellular proteins were analysed in PC supernatants on days 0, 3, 5, 7, and 9. During 5days of storage, PPA and PEVs continuously increased (P<0.0001). Platelet function was observed to remain stable within the first 5days (P=0.1751) and decreased thereafter. Comparison of all time points to day 0 revealed the identification of 136 proteins that were significantly changed in abundance during storage, of which 72 were expressed by platelets. Network analysis identified these proteins to be predominantly associated with exosomes (P=4.61×10-8, n=45 genes) and two clusters with distinct functions were found with one being associated with haemostasis and the other with RNA binding. These findings may provide an explanation for ATRs. SIGNIFICANCE: Changes in platelet concentrate (PC) supernatants during storage have been so far only poorly addressed and high abundant proteins burden the identification of quantitative changes in the secretome. We applied a high-throughput antibody microarray allowing for the sensitive quantification of 673 extracellular factors. PCs account for the highest number of adverse transfusion reactions (ATRs). ATRs have been demonstrated to be more frequent in older PCs and removal of the supernatant prior to transfusion reduces their occurrence. Comprehensive interpretation of the changing proteins in the secretome during platelet storage under blood banking conditions may help to identify mechanisms leading to the occurrence of adverse transfusion reactions.

Role of MicroRNA 126 in screening, diagnosis, and prognosis of diabetic patients in Egypt.

MicroRNAs (miRNAs), family of non-coding small RNAs, play a vital role in the regulation of blood glucose level. We aimed to investigate the relation of serum miRNA-126 expression with impaired glucose tolerance as well as type 2 diabetes mellitus (T2DM) patients with and without complications. One hundred healthy controls, eighty-six patients with IGT, and one hundred patients with T2DM were recruited in this study. Serum miRNA-126 expression was assessed by quantitative real-time polymerase chain reaction. We found a significant decrease of serum miRNA-126 expression between IGT patients as well as diabetic patients when both compared with controls and between diabetic patients compared to IGT patients. A significant decrease of serum miRNA-126 expression was detected in diabetic patients with complications compared to those without evident complications especially those with diabetic macrovascular complications and diabetic retinopathy. Serum microRNA-126 expression could be a good marker for diagnosis of IGT and T2DM as well as for monitoring the outcomes of such disease. © 2016 IUBMB Life, 68(6):452-458, 2016.

Identification of novel biomarkers in chronic immune thrombocytopenia (ITP) by microarray-based serum protein profiling.

The pathological mechanisms underlying the development of immune thrombocytopenia (ITP) are unclear and its diagnosis remains a process of exclusion. Currently, there are no known specific biomarkers for ITP to support differential diagnosis and treatment decisions. Profiling of serum proteins may be valuable for identifying such biomarkers. Sera from 46 patients with primary chronic ITP and 34 healthy blood donors were analysed using a microarray of 755 antibodies. We identified 161 differentially expressed proteins. In addition to oncoproteins and tumour-suppressor proteins, including apoptosis regulator BCL2, breast cancer type 1 susceptibility protein (BRCA1), Fanconi anaemia complementation group C (FANCC) and vascular endothelial growth factor A (VEGFA), we detected six anti-nuclear autoantibodies in a subset of ITP patients: anti-PCNA, anti-SmD, anti-Ro/SSA60, anti-Ro/SSA52, anti-La/SSB and anti-RNPC antibodies. This finding may provide a rational explanation for the association of ITP with malignancies and other autoimmune diseases. While RUNX1mRNA expression in the peripheral blood mononuclear cells (PBMC) of patients was significantly downregulated, an accumulation of RUNX1 protein was observed in the platelets of ITP patients. This may indicate dysregulation of RUNX1 expression in PBMC and megakaryocytes and may lead to an imbalanced immune response and impaired thrombopoiesis. In conclusion, we provide novel insights into the pathogenic mechanisms of ITP that warrant further exploration.

Affinity-based microarrays for proteomic analysis of cancer tissues.

Based on about a decade of technical developments in analysing the human proteome with antibody microarrays and experience in performing such analyses, now there are the means at hand for detailed and simultaneously global investigations of this kind. Many technical aspects have been dealt with of both the microarray format itself - such as overcoming kinetic and mass transport limitations and thus achieving accurate measurements - and ancillary processes - such as extraction procedures that provide good protein solubilisation, produce reproducible yields and preserve the native protein conformation as much as possible. The overall analysis process is robust and reproducible, highly sensitive down to the level of single-molecule detection and permits an analysis of several parameters on many molecules at a time. While the study of body liquids is widely applied, analyses of tissue proteomes are still scarce. However, conditions do exist to perform the latter at a quality level that meets the standards for clinical applications. This review highlights methodological aspects relevant for a biomedically useful analysis of cellular samples and discusses the potential of such studies, in particular, in view of personalised medicine approaches.

Robust protein profiling with complex antibody microarrays in a dual-colour mode.

Antibody microarrays are a multiplexing technique for the analyses of hundreds of different analytes in parallel from small sample volumes of few microlitres only. With sensitivities in the picomolar to femtomolar range, they are gaining importance in proteomic analyses. These sensitivities can be obtained for complex protein samples without any pre-fractionation or signal amplification. Also, no expensive or elaborate protein depletion steps are needed. As with custom DNA-microarrays, the implementation of a dual-colour assay adds to assay robustness and reproducibility and was therefore a focus of our technical implementation. In order to perform antibody microarray experiments for large sets of samples and analytes in a robust manner, it was essential to optimise the experimental layout, the protein extraction, labelling and incubation as well as data processing steps. Here, we present our current protocol, which is used for the simultaneous analysis of the abundance of more than 800 proteins in plasma, urine, and tissue samples.

Prostate tissue texture feature extraction for suspicious regions identification on TRUS images.

In this work, two different approaches are proposed for region of interest (ROI) segmentation using transrectal ultrasound (TRUS) images. The two methods aim to extract informative features that are able to characterize suspicious regions in the TRUS images. Both proposed methods are based on multi-resolution analysis that is characterized by its high localization in both the frequency and the spatial domains. Being highly localized in both domains, the proposed methods are expected to accurately identify the suspicious ROIs. On one hand, the first method depends on a Gabor filter that captures the high frequency changes in the image regions. On the other hand, the second method depends on classifying the wavelet coefficients of the image. It is shown in this paper that both methods reveal details in the ROIs which correlate with their pathological representations. It was found that there is a good match between the regions identified using the two methods, a result that supports the ability of each of the proposed methods to mimic the radiologist's decision in identifying suspicious regions. Studying two ROI segmentation methods is important since the only available dataset is the radiologist's suspicious regions, and there is a need to support the results obtained by either one of the proposed methods. This work is mainly a preliminary proof of concept study that will ultimately be expanded to a larger scale study whose aim will be introducing an assisting tool to help the radiologist identify the suspicious regions.

AT1-receptor blockade by telmisartan upregulates GTP-cyclohydrolase I and protects eNOS in diabetic rats.

Several enzymatic sources of reactive oxygen species (ROS) were described as potential reasons of eNOS uncoupling in diabetes mellitus. In the present study, we investigated the effects of AT1-receptor blockade with chronic telmisartan (25 mg/kg/day, 6.5 weeks) therapy on expression of the BH4-synthesizing enzyme GTP-cyclohydrolase I (GCH-I), eNOS uncoupling, and endothelial dysfunction in streptozotocin (STZ, 60 mg/kg iv, 7 weeks)-induced diabetes mellitus (type I). Telmisartan therapy did not modify blood glucose and body weight. Aortas from diabetic animals had vascular dysfunction as revealed by isometric tension studies (acetylcholine and nitroglycerin potency). Vascular and cardiac ROS produced by NADPH oxidase, mitochondria, eNOS, and xanthine oxidase were increased in the diabetic group as was the expression of NADPH oxidase subunits at the protein level. The expression of GCH-I and the phosphorylation of eNOS at Ser1177 was decreased by STZ treatment. Therapy with telmisartan normalized these parameters. The present study demonstrates for the first time that AT1-receptor blockade by telmisartan prevents downregulation of the BH4 synthase GCH-I and thereby eNOS uncoupling in experimental diabetes. In addition, telmisartan inhibits activation of superoxide sources like NADPH oxidase, mitochondria, and xanthine oxidase. These effects may explain the beneficial effects of telmisartan on endothelial dysfunction in diabetes.

Prostate cancer spectral multifeature analysis using TRUS images.

This paper focuses on extracting and analyzing different spectral features from transrectal ultrasound (TRUS) images for prostate cancer recognition. First, the information about the images' frequency domain features and spatial domain features are combined using a Gabor filter and then integrated with the expert radiologist's information to identify the highly suspicious regions of interest (ROIs). The next stage of the proposed algorithm is to scan each identified region in order to generate the corresponding 1-D signal that represents each region. For each ROI, possible spectral feature sets are constructed using different new geometrical features extracted from the power spectrum density (PSD) of each region's signal. Next, a classifier-based algorithm for feature selection using particle swarm optimization (PSO) is adopted and used to select the optimal feature subset from the constructed feature sets. A new spectral feature set for the TRUS images using estimation of signal parameters via rotational invariance technique (ESPRIT) is also constructed, and its ability to represent tissue texture is compared to the PSD-based spectral feature sets using the support vector machines (SVMs) classifier. The accuracy obtained ranges from 72.2% to 94.4%, with the best accuracy achieved by the ESPRIT feature set.

Bronchoscopic study on aetiology of chronic cough in HIV-infected adults with negative sputum smears for Mycobacterium tuberculosis at Kenyatta National Hospital, Nairobi.

OBJECTIVE: To establish the aetiology of chronic cough in HIV-infected patients with negative sputum smears for Acid Fast Bacilli (AFB). DESIGN: A cross-sectional descriptive study. SETTING: Kenyatta National Hospital, a tertiary referral centre in Kenya SUBJECTS: Sixty five HIV-infected adults presenting with chronic cough and negative sputum smears for AFBs. RESULTS: Sixty-two patients were included in the final analysis. Aetiology of chronic cough was established in 42 (68%) patients. Pneumocystis jiroveci, bacterial pneumonia and Mycobacterium tuberculosis were diagnosed in 22 (35.5%), 17 (27.4%) and 14 (22.5%) patients respectively. Majority (98%) of patients with a diagnosis had multiple causes established in them. Ciprofloxacin had activity against 91% of the isolated organisms while Penicillin was active against 35% only. CONCLUSION: This study documents Pneumocystis jiroveci pneumonia as a common cause of morbidity in a subset of HIV infected patients with chronic cough and negative sputum smears for AFB in Kenya.

Prostate cancer multi-feature analysis using trans-rectal ultrasound images.

This note focuses on extracting and analysing prostate texture features from trans-rectal ultrasound (TRUS) images for tissue characterization. One of the principal contributions of this investigation is the use of the information of the images' frequency domain features and spatial domain features to attain a more accurate diagnosis. Each image is divided into regions of interest (ROIs) by the Gabor multi-resolution analysis, a crucial stage, in which segmentation is achieved according to the frequency response of the image pixels. The pixels with a similar response to the same filter are grouped to form one ROI. Next, from each ROI two different statistical feature sets are constructed; the first set includes four grey level dependence matrix (GLDM) features and the second set consists of five grey level difference vector (GLDV) features. These constructed feature sets are then ranked by the mutual information feature selection (MIFS) algorithm. Here, the features that provide the maximum mutual information of each feature and class (cancerous and non-cancerous) and the minimum mutual information of the selected features are chosen, yielding a reduced feature subset. The two constructed feature sets, GLDM and GLDV, as well as the reduced feature subset, are examined in terms of three different classifiers: the condensed k-nearest neighbour (CNN), the decision tree (DT) and the support vector machine (SVM). The accuracy classification results range from 87.5% to 93.75%, where the performance of the SVM and that of the DT are significantly better than the performance of the CNN.

Simultaneous determination of artemether and its major metabolite dihydroartemisinin in plasma by gas chromatography-mass spectrometry-selected ion monitoring.

A sensitive, selective, and reproducible GC-MS-SIM method was developed for determination of artemether (ARM) and dihydroartemisinin (DHA) in plasma using artemisinin (ART) as internal standard. Solid phase extraction was performed using C18 Bond Elut cartridges. The analysis was carried out using a HP-5MS 5% phenylmethylsiloxane capillary column. The recoveries of ARM, DHA and ART were 94.9 +/- 1.6%, 92.2 +/- 4.1% and 81.3 +/- 1.2%, respectively. The limit of quantification in plasma was 5 ng/ml (C.V. < or = 17.4% for ARM and 15.2% for DHA). Calibration curves were linear with R2 > or = 0.988. Within day coefficients of variation were 3-10.4% for ARM and 7.7-14.5% for DHA. Between day coefficients of variations were 6.5-15.4% and 7.6-14.1% for ARM and DHA. The method is currently being used for pharmacokinetic studies. Preliminary data on pharmacokinetics showed Cmax of 245.2 and 35.6 ng/ml reached at 2 and 3 h and AUC0-8 h of 2463.6 and 111.8 ngh/ml for ARM and DHA, respectively.

Reconstruction of resected mandibles using a hydroxyapatite veterinary bone graft.

A newly developed bone equivalent hydroxyapatite was derived from veterinary bone (VHAP). Sections of 1 cm of six rabbit mandibles were equally replaced by this VHAP graft. Radiological studies by X-ray were performed pre-operatively, immediately, and 1, 2 and 3 months post-operatively. The graft host-bone interface was examined periodically by scanning electron microscopy (SEM). Accompanying structural changes of the graft 3 months post-operatively were compared with the pre-operative findings by infra-red (IR) spectroscopic analysis. Complete union of the biomaterial to the host bone after 3 months was evidenced radiologically. SEM proved complete graft integration. This was accompanied by a decrease in optical density of the IR analysis of post-operative VHAP, indicating some leaching of the ions. Clinically, the graft was completely incorporated in the mandible without any complications. We discuss the use of VHAP in humans to reconstruct post-surgical mandibular defects.

A histological study of the innervation of developing mouse teeth.

The innervation of developing mouse teeth between initial formation and crown formation was investigated using silver-stained serial sections. The developing innervation correlated with the stage of development of individual teeth rather than the chronological age of the mice. Nerves approached the developing dental papilla during the bud stage and formed a basal plexus below the dental papilla in the early cap stage. Nerve fibres from this plexus spread into the dental follicle as it began to develop. However, nerves did not enter the dental papilla until crown formation commenced, when the innervation was fairly rapid. Innervation commenced in the incisor teeth as soon as dentinogenesis started but not until a thin layer of enamel had been formed in the molar teeth. Although some of the early fibres were associated with blood vessels, many nerves lay free in the pulp. The absence of nerves in intimate relationship to the presumptive dental regions during the inductive phase of tooth development suggests that neural induction plays no part in the initiation of odontogenesis. However, it is not possible, from a purely histological study such as this, to attribute any function to the nerves at other stages of tooth development until the neurotransmitter content, and hence the type and likely function of the nerves, is established.